Gustavsvärn is the best kept part of a four-part fortress on an islet outside of Hanko. The fortress was built by the Swedes in the late 18th century, who added a lighthouse in 1951. The attendant’s house is well kept and maintainted by the Finnish Lighthouse Society, who sell souvenirs there in the summer.
Hauensuoli is a narrow strait between the islands Tullholmen and Kobben outside of Tulliniemi. There are over 640 rock carvings on the island. This “visitor’s book of the archipelago” consists the names and coats of arms of nobility, soldiers and tradesmen. The earliest ones are from the 16th century.